1. Field of the Invention
The present invention relates generally to optical positioners, and particularly to a positioning device for optical elements.
2. Technical Background
The alignment and structural attachment of miniature photonic components is a difficult technical problem. Many optical devices have optical tolerances that are large enough to allow the devices to be passively aligned with on another. In passive alignment optical elements are attached either to one another or to a substrate in predetermined locations. Active alignment is required for optical devices having closer optical tolerances. Active alignment is the process of placing an optical element in a desired location by perturbing its location while monitoring the impact of the perturbation on an optical signal. The optical element is repositioned until the optical signal achieves a desired value, e.g., insertion loss is minimized, or a certain waveband of light is transmitted or reflected.
Active alignment of optical elements is used in the construction of numerous optical devices in optical communication systems. Examples of which are alignment of filters in wavelength add/drop multiplexers, aligning lens with light sources, aligning collimators with one another, and optical waveguide fibers with optical devices such as planar optical circuits and active devices.
The active alignment of optical devices is complicated by the fact that after the optical element is positioned it must be fixed into place. During the operation of fixing the optical element in place the optical element must be free of unacceptable shifts in position. Positional shifts may occur in the positional fixing portion of the assembly process, for example, during the cure cycle of a thermally curable adhesive, due to the contraction or expansion of the adhesive.
The present invention facilitates the active alignment of optical elements by allowing for their manipulation in six degrees of freedom.
One aspect of the present invention is a positioner for an optical element. The positioner includes a base having a receptacle and a substantially planar surface slidably engageable with a substrate. The positioner also includes a mounting platform disposed in the receptacle. The receptacle constrains the mounting platform to translation in a direction substantially perpendicular to the substantially planar surface and the mounting platform is configured so as to be free to rotate about three orthogonal axes within the receptacle. The optical element is coupled to the mounting platform. The optical element is aligned with a second optical element by selectively positioning the mounting platform.
In another aspect, the present invention includes a positioner for an optical element. The positioner includes a base having a substantially planar surface slidably engageable with a substrate. The base also includes two vertical members. Each vertical member includes an arcuate surface and a slot. The arcuate surfaces of the two vertical members define a receptacle. A mounting platform is disposed within the receptacle. The mounting platform includes a curved surface. The curved surface allows the mounting platform to be selectively positionable by allowing the mounting platform to slide and rotate within the receptacle. The optical element is mounted to the mounting platform and is positioned by sliding and rotating the mounting platform within the receptacle and sliding the base on the substrate. After the optical element is positioned the mounting platform is coupled to the base and the base is coupled to the substrate.
In another aspect, the present invention includes a positioner for an optical element. The positioner includes a base slidably moveable on a surface. The base includes a substantially cylindrical receptacle. The positioner also includes a mounting platform disposed within the receptacle. The mounting platform includes an arcuate surface and is selectively positionable within the receptacle. The optical element is coupled to the mounting platform and is aligned with another optical element by translating and rotating the mounting platform within the receptacle and sliding the base on the surface, thus providing an alignment system with six degrees of freedom. After the optical elements are aligned the mounting platform is coupled to the base and the base is coupled to the surface.
In another aspect, the present invention includes a method for positioning an optical element. The method includes the steps of providing an optical element, the optical element having an optical axis and providing a mounting platform. The method further includes the step of coupling the optical element to the mounting platform. The method further includes the steps of providing a base, the base having a receptacle and placing the mounting platform in the receptacle, thereby forming an assembly. The method further includes the steps of placing the assembly on a surface and aligning the optical element in accordance with predetermined criteria. The method further includes the steps of coupling the assembly to the surfaces and coupling the mounting platform to the base. Wherein the step of aligning includes the steps of translating the assembly along the surface, translating the mounting platform within the receptacle and rotating the mounting platform within the receptacle.
The positioner for optical elements of the present invention results in a number of advantages over prior art positioners for optical elements. For example the positioner for optical elements of the present invention does not rely on non-elastic deformation of the positioner to maintain the alignment of optical elements.
Another advantage of the present invention is that the present invention may be used with robotic assembly systems thereby allowing the positioning of optical elements with great precision.
Another advantage of the present invention is that optical elements may be aligned and attached in a single assembly step, enabling automated assembly of optical devices.
Another advantage of the present invention is that the optical element being aligned is permanently fixed to the optical platform, ensuring the position and orientation of each optical element relative to other optical elements is maintained.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operation of the invention.